create mongodb list inside of a table - mongodb

Question

I want to create a chat app.
I need to decide how my DB is gonna look like.
I a m using mongodb as a DB.
I want to have a collection named "users" which will have every user that is registered for my app.
i.e.
users
- Mike
- David
- Adam
I also want to have a collection of rooms that are in my chat app.
i.e.
rooms
- Game of thrones
- Class of 94'
- sicence fiction
- pet lovers
I also want to have a collection of room with users
i.e.
pet lovers (room name)
- Mike (user1)
- Dave (user2)
.....
I know how to represent the users and rooms in mongodb.
But any idea how to represent the "users in room" collection? it seem I need a list inside a collection (list of users in room) in addition I need to save the room name.
I want it to be easy to pull data out of this collection (i.e. remove or add user to a room / find out which room a user is chatting in...)
also, if someone has a better suggestion to represent this data - feel free...
Thanks

Answer 1

you can add a users array that contains IDs of users in a given room to room document, so the rooms collection will something looks like:
[
{
"_id":"...",
"roomName":"Game of Thrones",
//...
"users":[
"userId1",
"userId2",
//...
"userIdn"
]
}, {
"_id":"...",
"roomName":"the secret zone",
//...
"users":[
"userId2",
//...
]
}
]
then, when a user join a room R, you'll add his ID to R.users array. and remove it when he left.
by the way, I think defining some schema model with mongoose may be helpful